Serine proteinase inhibitors and their role in the feeding cycle of Amblyomma americanum

Acarcides have caused a great deal of resistance as well as residual pollution that negatively affects non-target organisms. Tick control by the use of non-acarcides, such as vaccines, is viable and attractive alternative. To identify effective targets, the molecular physiology of ticks must be determined. We are studying the role of serine proteinase inhibitors (serpins) in the feeding cycle of Amblyomma americanum. Serpins have gained a lot of attention as potential target antigens because they act as negative regulators of key biological pathways, such as blood coagulation and inflammation. We have previously described 17 serpins (hereafter called Lospins), separated into four groups, from A.americanum. These Lospins are expressed early on in the feeding cycle (during preparatory and slow feeding phase). We anticipate that these are possible target antigens for tick vaccines as they are present before ticks begin to feed and transmit disease agents. Expression patterns (indicated by RT-PCR) determined ubiquitous expression of most of the Lospins in salivary glands, midgut, ovaries, and carcass. The objective of this project is the expression, localization, and biochemical analysis, both in vitro and in vivo, of a representative member from each of the four groups of Lospins. We have correlated the transcription patterns with protein expression though western blot analysis. Biochemical characterization of insect cell expressed Lospins and RNA interference analyses are in progress.